The invention relates to improvements in apparatus for removing calculi (such as gall stones, urinary calculi or renal calculi) from cavities of animal bodies, particularly human bodies. More particularly, the invention relates to improvements in apparatus for dissolving calculi in animal bodies prior to evacuation of dissolved calculi through an ureter, through the urethra or through another passage leading to or constituting a body cavity.
It is known to employ a cystoscope for introduction into an ureter of an apparatus for withdrawal of renal calculi. Such apparatus employ one or more loops or a spreadable element which must be applied around a calculus in the ureter. The spreadable element or the loops are thereupon weighted and/or otherwise pulled to gradually draw the renal calculus into the urinary bladder. A drawback of these apparatus is that their spreadable element and/or loops cannot properly engage all kinds of calculi, e.g., renal calculi which exhibit sharp edges and are firmly anchored in the ureter. Furthermore, even if the calculus is adequately engaged by one or more loops and/or by another suitable (e.g., spreadable) element, it is likely to cause injury to tissue around the ureter during extraction from the ureter into the urinary bladder. The tissue surrounding a renal calculus is also likely to be damaged during application of one or more loops and/or other engaging elements around a calculus which is rather firmly anchored in the ureter.
German patent application Serial No. 20 57 636 of Rudolf Necke (published Mar. 9, 1972) discloses an apparatus which is designed to evacuate concretions in a manner causing less trauma to the patient. The patented apparatus employs a twin-walled hose having a twin-walled inlet in the form of a calyx. The inlet is surrounded and maintained in collapsed condition by a sheath which is operative during introduction of the hose and inlet into an ureter close to a calculus but is thereafter withdrawn or retracted prior to admission of a gaseous or liquid medium between the walls of the thus exposed hose and between the walls of its inlet. The thus expanded inlet is then ready to guide the calculus into the hose during further introduction of the patented apparatus into the ureter. The configuration of the aforediscussed sheath is such that its front side is rounded while it confines and maintains the inlet of the hose in the collapsed condition. This reduces the likelihood of injury and of pronounced trauma during introduction of the apparatus into a body cavity adjacent to a calculus. The sheath can maintain the inlet in collapsed condition by folding or in a similar way. A cystoscope is utilized to introduce the apparatus into the ureter, and the introduction is monitored by the person or persons in charge to ensure that the forward progress of the hose is interrupted and the inlet is expanded shortly before the apparatus reaches the calculus. Expansion of the inlet is intended to ensure gradual and rather gentle expansion of the ureter with attendant loosening of the calculus which is then caused to enter the hose through the expanded inlet. The fluid pressure between the walls of the hose as well as between the walls of the inlet is thereupon reduced to cause gradual collapse of such parts and gradual narrowing (contraction) of the ureter. The collapsed inlet surrounds at least the major portion of the entrapped calculus during ensuing extraction from the cavity.
German patent application Serial No. 39 02 943 of Ulrich Leuschner et al. (published Aug. 9, 1990) discloses an apparatus which introduces a liquid solvent into a body cavity, especially into a gallbladder. The apparatus is further designed to evacuate by suction a mixture consisting of solvent, sludge of dissolved calculus and secretions of the gall. The evacuating means comprises a piston pump. Provisions are made to segregate the solvent from secretions by resorting to a suitable separator. A drawback of this patented apparatus is that, in contrast to the operation of the previously described apparatus employing a hose with a calyx-shaped inlet for a calculus, dissolution of the calculus in the interior of an animal body involves direct contact between the solvent and the body tissue. This can cause extensive damage to the tissue and/or to one or more organs.
The situation is similar in connection with apparatus which is disclosed in German patent application Serial No. 36 16 205 of Ulrich Leuschner (published Nov. 19, 1987). This patent discloses a twin-balloon catheter for selective admission of liquids into the gallbladder. The catheter is fixed in the bile duct and the latter is then sealed from above (i.e., from the liver) and from below (i.e., from the intestine). One of the balloons seals from the liver and the other balloon seals from the intestine. An opening between the two balloons then admits a suitable medium into the bile duct.
German Utility Model No. G 91 01 684 (owned by Andrea Scarfi and published Jun. 20, 1991) discloses a sac for extraction of substances from the stomach. This publication does not deal with the dissolution of calculi.
German patent application Serial No. 21 04 673 of Rudolf Necke (published May 31, 1972) discloses an apparatus for removal of urinary calculi and of calculi which are lodged in the lower part of the pelvis of a kidney. The apparatus employs an expandible calyx which can be introduced into the urinary tract to expand the urinary tract and to thus facilitate introduction of the calculus into the calyx. Once the calculus is confined in the calyx, the latter is caused to contract and to thus capture the calculus for extraction (in undissolved condition) from the body of a patient.